Passengers were held up for about an hour on the British side and 30 minutes on the French side on Tuesday, French news agency AFP reported.

Meanwhile, the UK has agreed to provide an extra £7m ($10.9m) towards efforts to step up security at the Channel Tunnel railhead in Calais, Home Secretary Theresa May has announced.

A spokesman for Eurotunnel said the migrants were trying to enter the site "between midnight and 6am", adding: "It was the biggest incursion effort in the past month and a half.

"All our security personnel, that is nearly 200 people, as well as police were called in."

Another Eurotunnel spokesman said: "There was some damage to our fences - which we'll have to repair - as they tried to board shuttles. Fortunately, there wasn't any damage to shuttles. Unfortunately, a number of people were injured.

"It is an almost nightly occurrence - we're trying to run a travel business here."